Flask for carbureting files or other cutting-tools



(No Model.)

M. A. HOWELL, Jr.

PLASK TOR CARBURETING FILES OR OTHER CUTTING TOOLS. No. 283,396.Patented Aug. 21, 1883.

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UNITED STATES PATENT 'EFICE...

MARTIN A. I-IOYVELL, JR, OF-CHICAGO, ILLINOIS.

FLASK FOR CARBURETING FILES OR OTHER CUTTlNG-TOOLS.-

SPECIFICATION forming part of Letters-Patent lll'o. 283,396, datedAugust 21, 1883.

Application filed March 17, 1883.

' Improvements in Apparatus for Deoxidating and Garbureting Files andother Cutting-Tool s,

of which the following is a specification.

This invention relates to the manufacture of cast-iron and steel files,screwtaps, dies, and

other cutting-tools.

The accompanying drawing is alongitudinal sectional view of a flask anda plan view of a gas-holder embodying my invention.

It is well known that no bar of steel can be heated and reheated duringthe forging of fileblanks without more or less oxidation upon itssurface and consequentloss of hardening power, which reduces thestandard of its quality; and, further, during the annealing process,which is requisite in file-making to soften the metal preparatory tosurfacing and cutting, the free carbon is oxidated, thus depriving themetal of its characteristic as a true carbide or carburet, anddecreasing its power of resistance when subsequently hardened andtempered.

In order to convert cast-iron into bar-iron, it is necessary to removethe carbou'and silicon associated with it. i This is done by heating itin contact with oxide of iron, whereby the carbon is evolved in the formof carbonic oxide, while the silicon, also combining with a portion ofthe oxide, is converted into silicic acid, which unites with anotherportion, forming a fusible slag which separates from the metal. In whitecastiron, however, the proportion of silicon is only about one per cent.This bariron may be again converted into cast-iron by restoring theproper percentage of carbon by cementation. In all the processesheretofore known, however, the metal has been heated in the presence ofboth carbon and oxygen, the latter being derived from the pressure ofatmospheric air. The consequence is that instead of the pure carbon,with which the metal was formerly combined, the known processes ofcementationrestore to the metal an oxide of carbon, and the presence ofoxygen causes an oxidation of the surface of the metal ,which, in theprocess of converting a tool having a cutting edge or edges orcutting-teeth frombar- (No model.)

iron back to white cast-iron, would entirely defeat the object of myinvention by reason of the brittleness of the oxide.

The object of my invention is to avoid the above objections and toprovide effl cient means for producing files and other cutting-tools ofgreater durability and tenacity than heretofore, whereby the carbon andmetal are both deprived of the injurious effects of oxidation incurredduring the steps they must necessarily pass in forging and annealing.

The object of my invention I accomplish in the manner and by the meanshereinafter described and claimed, reference being had to theaccompanying drawing, in which the figure'is a lon itudinal sectionalview of a flask 1 a I or retort embodying my invention.

The flask is constructed in the form of a hol- 10W cylinder, number 1,with a permanentlyclosed end, 2, and at its other end is provided withan annular tapering collar, 3, surround ing its mouth 4. The cover 5 forthe flask is constructed with an annular proj ectingflange, 6, madeflaring or tapering on its internal surface to accurately fit over thetapering collar 3, being clamped and firmly held thereon through themedium of a spring-yoke, 7, the arms of which are provided with lugs toengage the rear edge of the collarfi, and a screw, 8, passing through athreaded socket, 9, in the yoke, and bearing at its inner end directlyagainst the cover, all in such manner that the mouth of the flask issealed to secure the same from leakage of air or the gas with which theflask is to be charged.

In one end of the flask is a pipe or tube, 10, provided with a cook orvalve, 11, such pipe or tube preferably passing through the cover, andadapted to connect with a reservoir or gas-holder, 14,. containing purehydrocarbon vapor, or its equivalent, under pressure, and so jointedadjacent to the cook or valve that the .pipe can be separated at thatpoint to disconnect the flask from the gas-holder, when the flask isremoved from the furnace, as herein after explained. The flask isprovided with a vent-tube, 12, )referably passing through the cover andprovided with a cock-:ior valve, 13.

The flask may be made of wrought or eastiron, but preferably of analloyzconsisting of iron and nickel to avoid oxidation of the flask rwhere the oxidated metal is left, as in the usual drochlorate ofammonia, 850.; but I prefer to at a high heat, the relative proportionsin l which these two metals 'enter into the alloy being preferably onepart of nickel to four or five parts of iron.

The file-blanks having been formed by forging and annealing to softenthe metal, they are surfaced and cut by any of the well-known methods,and afterward arranged within the flask, which is then placed in amuffle or furnace and connected with the gas-holder. The vent-cock 13and valve 11 being opened, a cur-. rent of pure hydrocarbon vapor willpass into the flask and expel all air therefrom through the vent-cockuntil, by the lighting of the flame at the mouth of the vent-cock, theevidence of the purity of the vapor and its freedom from oxygen isassured, when the venteock is closed and the files held in an atmosphereof pure hydrocarbon vapor free from oxygen until a high annealing-heatis reached. The vent cock is again opened. The pressure is now increasedat the reservoir or gas-holder until the operation of deoxidation andcarburization is completed, which, at the proper heat, can be effectedin one hour. The flask is then disconnected from the gas holder, sealedby closing. the valve 11, and withdrawn from the muffle and permitted tocool with the contents enveloped in the deoxidating and carburetingvapor, the flask not being opened until the contents are cold.

If the flles being, treated are made of castiron, the metal will berestored to a true carbide or carburet, while if the files are made ofsteel the metalwill be restored to its true character, exhibiting thecharacteristics of a true carbide or carburet. The files are by themeans described brought to a standard of extreme durability, and arehardened and tempered in the usual manner. A file deoxidized andcarbureted by the means described can be hardened and tempered at a muchhigher degree of heat without burning than is possible annealingprocess, a simple oxide. I have employed chemical equivalents ofhydrocarbon vapor to accomplish the desired obj ect-su ch as carbonicoxide, carbonate of ammonia, hy-

use a simple but pure vapor of hydrocarbon.

In the process of annealing cast-iron in the presence of oxides or othermatter having an affinity for carbon more or less of the free carbonremains in an oxidated condition. Now,

by the final process of conversion in an atmosphere of hydrocarbon vaporby the exclusion of all traces of oxygen the oxidated carbon is steel.

entirely deoxidated, leaving the metal a true carbide of irona standardimpossible to be reached by any known process in manufacturing steel.Steel, therefore, is not a true carbide, as supposed by scientists, butan oxidated carbide of iron. In an oxidated carbide part of the carbonis combined with the metal and ing gradually, is plainly seen in allannealed XVhen the carbon is wholly combined,

as in pure white iron or a true carburet, no process of annealing willshow any carbon crystallized between the particles of iron. Nor can itbe oxidated at a point below fusion, and

in many cases until the heat is raised beyond the point'of fusion.

The flask, being portable, is readily removed from the furnace ormuffle, which is an essential feature, to permit their gradual coolingwhile sealed to prevent the admission of air, the blanks not beingremoved until they are cold, up to which time they are surrounded by thevapor of hydrocarbon.

Having thus described my invention, what I claim is- 1. Asa means forconverting tool-blanks into a pure carburet, a portable flask having acover hermetically sealing the same, combined with a hydrocarbon-gasholder and means for connecting the flask with and disconnecting it fromthe gas-holder, substantially as and for the purpose described.

2. The combination of a portable flask adapted to be placed in andremoved from a furnace or muffle, and having a' cover for hermeticallysealing the same, with a hydrocarbon gas holder, a valved pipe forconnecting the flask with and disconnecting it from the gas-holder, anda valved vent-tube, substantially as described.

In testimony whereof I have hereunto set my hand in the presence of twosubscribing witnesses.

MARTIN A. HOWELL, JR. VVitnessesi THoMAs H. HowELr, JOHN WV. HOWELL.

The annealing-heat will,

